Makaburi, was a vocal supporter of Osama bin Laden and had described last year's attack on the Westgate shopping mall in Nairobi, which was claimed by Somalia's Al-Qaeda-linked Shebab rebels, as "100 percent justified."

Makaburi was also on UN sanctions lists and accused of being a "leading facilitator and recruiter of young Kenyan Muslims for violent militant activity in Somalia", and for having "strong ties" with senior Shebab members.

Senior police officer in Mombasa Richard Ngatia confirmed Makaburi, had been killed by "unknown assailants", and an AFP reporter in the city saw his bloodied corpse.

Makaburi, dressed in white robes, had been shot in the chest. Another young man was also shot dead alongside Makaburi, in circumstances that were not immediately clear.

"One of them is the body of Abubaker Shariff alias Makaburi," Ngatia told reporters, adding that family members had identified the body.

"They were waiting for a car to pick them up when people in a passing car shot at them. We don't know who killed them and why. We shall conduct an investigation," he said.

Many of the clerics' supporters accuse the Kenyan authorities of being behind a string of killings of radical Islamists in the Mombasa and Muslim-majority coastal region, claims that officials have repeatedly denied.

There were angry scenes outside the police station where the body had been taken, and police fired into the air to push back furious supporters of the cleric.

Mohamed Ali, who described himself as a "long-time friend of Makaburi", said he was with the cleric during the shooting, which occurred outside a Mombasa courthouse.

"We were expecting to be picked up outside the court, when we heard sudden gunshots. We all went to the ground," he said.

Vocal Al-Qaeda supporter:

In an interview with AFP only last month, Makaburi said he was resigned to being killed: "My life is in danger. They will eventually kill me. They do that," he said.

A prominent leader at the controversial Musa Mosque, a scene of frequent unrest in Mombasa,Makaburi presented himself as a simple man promoting "true Islam", and said the best examples of Islam are found in parts of Fallujah in Iraq, Taliban-controlled Afghanistan and Shebab-held areas of Somalia.

He also blasted Saudi Arabia as "a Christian country ruled by somebody who pretends to be a Muslim".

The firebrand cleric, who was in his 50's, had praised the suicide commandos who stormed Nairobi's part-Israeli-owned Westgate mall in September, massacring at least 67 in a four-day siege that was carried out in retaliation for Kenya's intervention in Somalia to fight the Shebab.

"It's our innocents for your innocents. It was justified. As per the Koran, as per the religion of Islam, Westgate was 100 percent justified," Makaburi told AFP.

Previous killings of clerics have sparked deadly riots, with supporters clashing with the police.

In August 2012, radical preacher Aboud Rogo Mohammed was gunned down, and in October last year his successor, Sheikh Ibrahim Ismail, met the same fate on a road near Mombasa, again sparking riots.

The killing of Makaburi comes just over a week after six worshippers were shot dead in a church near Mombasa, prompting a fresh security crackdown by Kenyan security forces and renewed talk among officials of a "shoot to kill" policy to deal with the threat of Islamist violence.

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